There are several types of test systems currently used for the serological detection of certain infectious diseases. These include the following:
1. Latex particle agglutination (LPA). PA1 2. charcoal particle agglutination (CPA). PA1 3. hemaagglutination (HA). PA1 4. complement Fixation (CF). PA1 5. fluorescent Antibody (FA). PA1 6. counter-electrophoresis (CEP). PA1 7. double diffusion (DD). PA1 8. radioimmunoassay (RIA). PA1 9. peroxidase tagged antibody (PTA).
Most of these tests are limited by one or more or all of the following limitations: (1) sensitivity; (2) complexity of the test procedure; and requirements for unstable reagents; (3) the carrier itself is unstable; (4) reagents may be dangerous; (5) the requirement for expensive equipment and thus experience in their operation; and (6) lack of specificity of the specific antigen used.
The sensitivity and the utility of or ease of running a serological test is of major importance as each characteristic may be cross-dependent in some ways and may be mutually independent in other ways. Usually, as the system's sensitivity becomes greater, the more complex it is and thus the requirement for more sophisticated equipment. Sensitivity of serological tests may be looked at at levels. These include a moderate range of sensitivity, which include DD, CPA, LPA and CE; mid-range which include HA, CF, FA and PTA, and ultra-low which includes RIA. Thus it is noted that there are several test systems that fit into the mid-range of sensitivity, but these are severely limited by unstable reagents and/or the requirement for use of complex equipment. Advantageously, however, the present invention can be used in the mid-range area of sensitivity, however it is not limited to this level, but can be used in the lower sensitivity range.
For a review of the development and evolution of immunological methods and their use as diagnostic laboratory tools, reference is made to "Immunology As a Laboratory Tool" by Frans Peetoom, M.D., PhD, appearing in the American Journal of Medical Technology, Volume 37, No. 12, Dec. 1971, pp. 455-469.